Mozilla developers reported memory safety bugs present in Firefox 76.

published 2020-07-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4723

cvss: 8.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits: 0; none known

Mozilla developers reported memory safety bugs present in Firefox 76. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 77.

Patch / fix

fixed in 1 distros 4

Mozilla Firefox 77

ubuntu opensuse alpine arch linux

firefox Ubuntu 16.04 LTS 77.0.1+build1-0ubuntu0.16.04.1
firefox Ubuntu 18.04 LTS 77.0.1+build1-0ubuntu0.18.04.1
firefox Ubuntu 20.04 LTS 77.0.1+build1-0ubuntu0.20.04.1

ubuntu advisories UBUNTU-CVE-2020-12411

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1

firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 77.0-r0
librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 77.0-r0

alpine advisories ALPINE-CVE-2020-12411

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox Arch Linux 77.0-1

arch linux advisories AVG-1173

Exploit prediction

1.17% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD	2.0	9.3	AV:N/AC:M/Au:N/C:C/I:C/A:C

Affected products

Mozilla Firefox

Classification

Weakness

CWE-787 Out-of-bounds Write

References

mozilla.org /security/advisories/mfsa2020-20/
vendor-advisory
bugzilla.mozilla.org /buglist.cgi?bug_id=1620972%2C1625333
issue-tracking, permissions-required, vendor-advisory

Sources

CVE List CVE-2020-12411
NVD CVE-2020-12411

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary